High speed tubular spinning of fine viscose rayon yarn



Nov. 23, 1965 HiDEO HATA ETAL 3,219,740

HIGH SPEED TUBULAR SPINNING OF FINE VISCOSE RAYON YARN Filed May 21,1962 COAGULAT/NG L/OU/D STRETCH/N6 MEMBER 2 6/ 6 W0 1.. N F /mu m CF/RST ROTA Tl/VG MEMBER TANG'E/VT/AL FLOW TUBE WOUND Y4 RN INVENTORH/DEO HA 7/] H/TOSH/ TONAM/ ATTORNEY United States Patent 3,219,740 HIGHSPEED TUBULAR SPINNING OF FINE VISCOSE RAYON YARN Hideo Hats, HitoshiTonarni, and Ryuichiro Koide, Iwakuni-slii, Yamaguchi-ken, Japan,assignors to Teihoku .linzo Kenshi Kabushiki Kaisha, Osaka, Japan, acorporation of Japan Filed May 21, 1962, Ser. No. 196,500 Claimspriority, application Japan, May 23, 1961,

8 Claims. (Cl. 264-180) This invention relates to .a high speed tubularmethod of spinning fine viscose rayon yarn.

Nowadays when the trend is for high-class fabrics, there is also ademand for fine yarns in case of rayon also. However, the finer the yarnbecomes, the quantity produced per unit spindle falls and as a resultraises the cost. Thus, there is an urgent demand for the high speedspinning of fine yarn Whose yarn quality equals or surpasses that of theordinary yarn.

The present invention has answered this demand, being related to amethod of spinning at high speeds of above 180 m., particularly above200 111. per minute, a fine yarn of less than 75 deniers. According tothis *invention, even a fine yarn of such as 20 deniers can be spun atabove 200 m. per minute and moreover with a yarn quality equal to orsurpassing that spun by the conventional method.

Heretofore, as the method of spinning at relatively high speeds viscoserayon yarn, particularly high tenacity yarn, the so-called tubularspinning method such as that described, for example, in F. R. MilhiserUS. Patent 2,440,057 was known.

The Millhiser method of spinning viscose rayon yarn comprises extrudingviscose through a spinneret into a coagulating bath to produce acontinuous filament yarn, stretching the resulting yarn at a tension notto exceed 0.06 gram per denier until said tension will no longer imparta substantial stretch to the yarn, causing coagulating bath to flow inthe direction of movement of the yarn, maintaining said yarn incocurrent contact with said coagulating bath at a tension of between0.01 and 0.06 gram per denier until it will withstand a tension of atleast 0.5 gram per denier, with the yarn travelling at a speed slightlyin excess of the speed of the cocurrent coagulating bath liquid, andthen stretching said yarn. When tubular spinning is carried out at aspinning speed of above 200 m./min., the how of the liquid is bound tobecome to a certain extent a turbulent flow. This is because no matterhow much the other conditions are controlled the Reynolds number of theliquid flow becomes more than 5000 and also because the yarn passesthrough the liquid. If the yarn is caused to maintain contact with thecoagulating bath liquid for a long period of time until it willwithstand a tension of 0.5 gram per denier, the yarn will be imparted aconsiderable amount of a nonuniform permanent deformation by means ofthis turbulent flow and the yarn quality will be lowered. In spite ofthis, in the Millhiser process the yarn had to be maintatined in contactwith the coagulating bath liquid for a relatively long period of time(until it will withstand a tension of 0.5 gram per denier). This isbelieved to be due to the following reason.

In a thick yarn of about 150 deniers such as shown in the example of theMillhiser process, when the diameter of the tube is small the yarn rubsagainst the tube wall and the yarn quality is impaired. Thus, forpreventing this, the diameter of the tube must necessarily be madelarge. In such a case, since the amount of liquid that is discharged atthe outlet of the tube becomes large, the force that the yarn issubjected to when it separates from the liquid also becomes large. Theyarn must have become such that it can withstand this force. And sincethe finer the yarn or the more the spinning speed is raised the forcethat the yarn is subjected to when it separates from the coagulatingbath liquid becomes greater, the necessity arises of imparting to theyarn a strength sufiicient to withstand this force.

Therefore, it is very difficult to spin at high speeds fine yarn of lessthan deniers by following the Millhiser process.

Accordingly, one of the principal objects of the present invention is toprovide a method of manufacturing fine viscose rayon yarn of less than75 deniers.

Another object of the invention is to provide a method of manufacturingat high speeds fine viscose rayon yarn of less than 75 deniers.

A further object of the invention is to provide a tubular spinningmethod of viscose rayon yarn that can spin fine yarn of good quality athigh speeds.

Other objects and advantages of the present invention will becomeapparent from the following description when taken in connection withthe accompanying drawing, in which:

FIGURES 1 and 2 illustrates two embodiments for carrying out the processof the instant invention.

FIGURE 3 illustrates the tangential flow of the coagulating fluid withrespect to a first rotating member.

FIGURE 4 illustrates a non-tangential flow of coagulating fluid.

These objects and advantages of this invention, as describedhereinabove, are attained in the tubular spinning of fine viscose yarnof less than 75 deniers comprising extruding viscose through a spinneretinto a coagulating liquid thereby forming continuous filament yarn,passing said yarn through a tube together with the coagulating liquid,discharging said yarn from said tube together with the coagulatingliquid and winding up said yarn on a first rotating member followed bystretching said yarn, by a method characterized in that the viscose isextruded into the coagulating liquid in such a manner that the draft Dsatisfies with respect to the peripheral speed V m./min. of a firstrotating member the condition that said tube whose diameter throughoutits entire length is substantially the same has an inside diameter of3-7 mm, that said yarn and coagulating liquid are passed through thetube at substantially the same speed, that the regeneration value of theyarn at the time of its being wound up on the first rotating member isbelow 20%, and that said first rotating member is disposed tangentiallyto the line of the coagulating liquid and has a peripheral speed V of-300 m./min.

What is referred to as the draft in this invention is represented by avalue that is obtained by dividing the peripheral speed of the firstrotating member with the average speed of the viscose in the holes whenit is being extruded from a spinneret.

And the spinning speed is represented by the peripheral speed of thatrotating member located immediately before the windup means, thisnormally being the second rotating member which follows the effecting ofstretching operations.

What is referred to as the regeneration value is represented by theformula l-residual '7 value of the yarn/'y value of viscose, the "pvalue of viscose being measured by the conventional film method or ionexchange method. The residual '7 value of the yarn was measuredaccording to the following procedure.

Namely, a V-shaped inclining bath through which is flowed a regenerationstopping liquid (an aqueous solution of sodium chloride and sodiumacetate) maintained at below C. is disposed between the first and secondrotating members, and the yarn is wound up on the second rotating memberto collect the sample. This is immediately washed thoroughly with acooled saturated aqueous solution of sodium chloride (a completelyneutral one being used), added to an aqueous sulfuric acid solution ofknown concentration, followed by thoroughly heating with shaking in awater bath and thereafter measuring the decrease in concentration of thesulfuric acid. The regeneration value at the time when the yarn is to bewound up on the first rotating member is represented by a value obtainedby measuring several times after having changed the number of turns onthe first rotating member and extrapolating for the value of the zeronumber of turns.

The rate of flow is indicated with the rate of flow of the liquid atthat part inside the tube where the yarn passes.

The first essential of this invention resides in the point that theregeneration value of sodium cellulose Xanthate in the yarn does notexceed 20% at the time when the yarn is to be wound up on the firstrotating member. Thus, in the present invention, since the residencetime of the coagulated yarn in the turbuelnt zone is short and moreovera yarn of small regeneration value is not easily imparted permanentdeformations, the lowering in yarn quality due to turbulent flow can beavoided. However, the strength of a yarn with a regeneration value below20% is not entirely sufficient and when such a yarn is discharged in alarge amount from the tube together with the coagulating liquid,breakage in the yarn occurs. We have solved this point by making theinside diameter of the tube 3-7 mm. thereby reducing the amount of thecoagulating liquid whereby has been made possible a reduction in theforce that the yarn is subjected to when separating from the liquid. Inaddition, by disposing the first rotating member tangentially to theoutflow of the: coagulating liquid, we have succeeded in lessening stillmore the force that the yarn is subjected to when separating from theliquid. In this instance, if the tube is held in. a position thatinclines 45-90 degrees to the horizontal plane, it is still moredesirable. At high speed spinning, of such as above 200 m./min., asbreakage of the yarn at that part near the spinneret is likely to occurvery frequently, it is necessary that the draft D be made small suchthat it will satisfy the condition V'+200D 4l0. Although making thedraft small is practiced in spinning high tenacity yarn, in case ofordinary yarn it is not generally practiced.

According to the present invention, since the spinning speed is fast,the distance that the yarn travels, after extrusion of the viscose and acoagulated skin of a hardness that determines the sectionalconfiguration of the viscose forms on its surface, becomes greater.Because the yarn is disturbed by the flow of the liquid While theforegoing coagulated skin is still soft, it inevitably results that thehigher the speed, the flatter the sectional configuration of the yarnbecomes. Hence, in the present invention it is best to provide acoagulating bath such as will form the coagulated skin promptly. If theconcentration of the sulfuric acid (g./l.) in the coagulating bath isless than 1.7 times the concentration of the total alkali (g./1.) in theviscose, drawbacks such as flattened section, unsatisfactry state ofspinnin-g, etc. occur.

On the other hand, if it is more than 2.6 times, filament formation inwhich regeneration has preceded by means of H SO occurs whereby loweringof the yarn quality, especially a rise in the swelling value, results.Therefore, the sulfuric acid concentration in the coagulating bath ispreferably 1.7-2.6 times, particularly 2.0-2.3 times, the concentrationof the total alkali in the viscose. Moreover, in case of a spinningmethod in which the sulfuric acid concentration is comparatively high,if the concentration of salts (g./l.) in the coagulating bath is lessthan 1.8 times that of the sulfuric acid, the regenerative effects willprecede the coagulation. On the other hand, if the concentration ofsalts is more than 2.7 times, the coagulation effects will precede.Therefore, the concentration of salts in the coagulating bath shouldpreferfably be 1.8-2.7 times, particularly 2.1-2.4 times that of thesulfuric acid.

Preferred as the temperature for the coagulating liquid is a temperaturesomewhat higher than that of the conventional coagulating liquid forviscose. That is to say, the temperature of the coagulating liquid maybe from 55 to 60 C.

As regards the tube employed in this invention, what is meant by aboutthe same diameter throughout its length is that it does not taper norflare toward its front end; the inlet for the yarn however includesthose that are flared for prevent-ing the setting up of a turbulentflow. The reason why the diameter of the tube must be uniform is thatwhen it is not, changes in the rate of flow occur, and the yarn issubjected to nonuniform stretching or shrinkage thereby lowering itsyarn quality.

And it is preferred that this tube extend over almost the whole of thedistance through which the yarn passes through the flow, the reasonbeing that, if the tube is rnade short and the liquid discharged, theliquid would not behave with a forced uniform motion due to the tubulardiameter but would gradually increase its speed due to gravitationalacceleration, resulting in stretching the yarn by the liquid flow. Thestretching of such an incompuetely coagulated yarn would not only resultin impairing the yarn quality but also in disturbing the state ofspinning.

After leaving the tube, preferably immediately after leaving the tube,the yarn which has been separated from the coagulating liquid is Woundup on the first rotating member that rotates at a peripheral speed of150-300 m./min., after which it is stretched between the first rotatingmember and the second rotating member. If desired, a still anotherrotating member may be provided besides the first and second rotatingmembers. While normally the stretching performed is about 20-40%, ifnecessary, it may exceed 40%.

As the foregoing first and second rotating members, the use of reels arepreferred. Furthermore, the yarn that has come off the second rotatingmember is preferably Wound up on a bobbin.

To further illustrate the present invention, the following examples willbe given.

EXAMPLE 1 After having manufactured the sodium cellulose Xanthate fromordinary rayon pulp by conventional procedures, it was dissolved withdiluted caustic soda thereby obtaining viscose. This viscose containedin 1 liter thereof 92 grams of cellulose and 54 grams of caustic soda,and its Hottenroth number was 11.5. Employing a coagulating bath whosetemperature was 48 C. and which contained g./l. of sulfuric acid, 280g./l. of sodium sulfate and 20 g./l. of zinc sulfate, a yarn of 30 totaldeniers and 15 filaments was spun. The tube used was 48 cm. in length,the diameter at the opening flaring to an inside diameter of 10 mm. withthe rest of the tube having an inside diameter of 4 mm.

The tube was disposed substantially perpendicularly and in a position 10mm. from the spinneret and 10 mm. away from the horizontal line passingthrough the center of the reel (the immersion length becomes 50 cm.). Inthis instance, the tube was made to about coincide with the tangent lineto the reel at the point where the yarn is wound up on the reel. Theregeneration value of the sodium cellulose xanthate in the yarn was13.2-15.1% when it was being wound up on the first rotating member. Thestate of spinning and the ratio of fluify spool when various changeswere made in the periphenal speed of the first rotating member, thespinning speed and the draft are shown in Table I.

Table I Peripheral Ratio of Speed of First Spinning Stretching DraftStetepf Flufiy Rotating Speed Ratio (D) V+200 D Spinning Spools Member(V (rm/min.) (Percent) (Percent) mJmin.)

The state of spinning is indicated by the number of 15 bath theregeneration Value of the yarn was changed and breaks per spindleoccurring in the yarn within a 24-hour period, while the ratio of flutfyspools indicates the percentage of the fluffy spools of spun yarnspools.

When spinning was carried out under the conditions in which theperipheral speed of the first rotating member was 239 m./min., thespinning speed, 300 m./min. and the draft, 0.72, as shown in Table I,and a hook was disa 75 de-33 filament yarn was spun.

In this instance, the tube which had an inside diameter of 6 mm. was sodisposed that it inclined 23 to the perpendicular and so that the yarnwould flow down in the 20 direction tangent to the upper side of thefirst rotating member.

The properties of the so obtained product are as shown in Table III,below.

"Measured at the time the yarn is being wound up on the first rotatingmember.

posed between the tube and the first rotating member whereby the yarnwas spun by being caused to change its direction at an angle of about135 C., the results obtained thereby are shown as No. 1 in Table II; andthe results obtained by using a tube with an inside diameter of 8 mm. inperforming the spinning are shown as No. 2 in the same table.

Table 11 Method of No. 1 No. 2

Table 1 Method Method State of Spinning 0.13 l 7.20 11.4 Ratio of FluffySpools percent 1.13 l 100 100 EXAMPLE 2 Viscose was prepared employingthe same procedures as in Example 1. In this instance, the concentrationof caustic soda in the viscose was 59 g./1. Spinning was per formed witha draft of 0.83 and a spinning speed of 280 55 As apparent from TableIII, in case of that in which the immersion length is 15 cm. and whoseregeneration value is very low, slight fluff occurs as a result of theforce to which the yarn is subjected when it is being removed from theliquid. On the other hand, when the regeneration value exceeds 20%, theelongation of the yarn obtained decreases due to the resistance of theliquid in the tube.

EXAMPLE 3 Sodium cellulose xanthate was prepared by the same proceduresas described hereinbefore and then dissolved in dilute NaOH. With thecellulose concentration in the viscose being 92.0 g./l. and with therespective instances in which the NaOH concentrations were 54 g./l. and66 g./l. spinning was carried out varying in many ways theconcentrations of H 50 and that of N1a SO +ZnSO (salts concentration).The sectional configuration of the yarn and the state of spinning thatresulted thereby are shown in Table IV.

The yarn spun was 50 (16/18 fils. The draft was 0.94, and the tubehaving an inside diameter of 6.5 mm. was disposed at an inclination 30from the perpendicular. The spinning speed was 280 m./min., with thestretching ratio being 32%.

Table IV Caustic Soda Sulfuric Acid Salts Cone. of Sulfuric Acid SaltsCone] cone. of Cone. of Coagulating Cone/Caustic Sulfuric Yarn SectionState of Viscose (g./l.) Ooagulating Bath (g./l.) Soda Cone. Acid Cone.Spinning Bath (g./l.)

180 1. 83 1. 89 Very flat. 0.38 230 2. 40 1. 84 Considerable 0. 17

unevenness. 125 280 2. 40 2. 24 Almost circular 0. 06

and substantially perfect. 120 270 l. 79 2. 25 Very flat. 0. 25 270 2.20 1. 86 Unevenness 0. 13

excessive. 145 370 2.20 2. 55 Almost circular and substan- O. 03 tiallyperfect.

Having thus described the nature of the invention, What is claimed is:

1. In the tubular spinning of fine viscose yarn of less than 75 denierswhich comprises extruding viscose through a spinneret into a coagulatingliquid thereby forming continuous filament yarn, passing said yarnthrough a tube together with the coagulating liquid, discharging saidyarn from said tube together with the coagulating liquid and Winding upsaid yarn on a first rotating member followed by stretching said yarn,the method characterized in that the viscose is extruded into thecoagulating liquid in such a manner that the draft D satisfies withrespect to the peripheral speed V m./min. \of a first rotating memberthe condition V+200D 410, Ithat said tube whose diameter throughout itsentire length is substantially the same as an inside diameter of 3-7mm., that said yarn and coagulating liquid are passed through the tubeat substantially the same speed, that the regeneration value of the yarnat the time of its being Wound up on the first rotating member isbetween 8 and 20%, and that said first rotating member is disposedtangentially to the line of the exit flow of the coagulating liquid outof the tube and has a peripheral speed V of 150-300 m./min.

2. The method according to claim 1 in which the sulfuric acidconcentration (g./l.) in said coagulating liquid is 1.7-2.6 times thetotal alkali concentration (g./l.) in the viscose, and the concentrationof salts (g./l.) in said coagulating liquid is 1.8-2.7 times saidsulfuric acid concentration.

,3. The method according to claim 2 in which the sulfuric acidconcentration (g./l.) in said coagulating liquid is 2.0-2.3 times thetotal alkali concentration (g./l.) in the viscose, and the concentrationof salts in said coagulating liquid is 2.1-2.4 times said sulfuric acidconcentration.

4. The method according to claim 1 in which said tube extendssubstantially over the whole of the yarn immersion zone.

5. The method according to claim 1 in which said tube is disposed suchthat it inclines -90 degrees to the horizontal plane.

6. The method according to claim 1 characterized in that a secondrotating member is provided subsequent to said first rotating member andsaid yarn is stretched 20-40% between said first and second rotatingmembers.

7. The method according to claim 6 in which reels are used as said firstand second rotating members.

8. The method according to claim 7 characterized in that the yarnleaving said second rotating member is Wound up on a bobbin.

References Cited by the Examiner UNITED STATES PATENTS 2,440,057 4/1948Millhiser 18-54 2,511,699 6/1950 Drisch et al. 264-188 3,084,021 4/1963Morimoto 264-197 ALEXANDER H. BRODMERKEL, Primary Examiner.

WILLIAM J. STEPHENSON, Examiner.

1. IN THE TUBULAR SPINNING OF FINE VISCOSE YARN OF LESS THAN 75 DENIERSWHICH COMPRISES EXTRUDING VISCOSE THROUGH A SPINNERET INTO A COAGULATINGLIQUID THEREBY FORMING CONTINUOUS FILAMENT YARN, PASSING SAID YARNTHROUGH A TUBE TOGETHER WITH THE COAGULATING LIQUID, DISCHARGING SAIDYARN FROM SAID TUBE TOGETHER WITH THE COAGULATING LIQUID AND WINDING UPSAID YARN ON A FIRST ROTATING MEMBER FOLLOWED BY STRETCHING SAID YARN,THE METHOD CHARACTERIZED IN THAT THE VISCOSE IS EXTRUDED INTO THECOAGULATING LIQUID IS SUCH A MANNER THAT THE DRAFT D SATISFIES WITHRESPECT TO THE PERIPHERAL SPEED V M./MIN. OF A FIRST ROTATING MEMBER THECONDITION V+200D<410, THAT SAID TUBE WHOSE DIAMETER THROUGHOUT ITSENTIRE LENGTH IS SUBSTANTIALLY THE SAME AS AN INSIDE DIAMETER OF 3-7MM., THAT SAID YARN AND COAGULATING LIQUIED ARE PASSED THROUGH THE TUBEAT SUBSTANTIALLY THE SAME SPEED, THAT THE REGENERATION VALUE OF THE YARNAT THE TIME OF ITS BEING WOUND UP ON THE FIRST ROTATING MEMBER ISBETWEEN 8 AND 20%, AND THAT SAID FIRST ROTATING MEMBER IS DISPOSEDTANGENTIALLY TO THE LINE OF THE EXIT FLOW OF THE COAGULATING LIQUID OUTOF THE TUBE AND HAS A PERIPHERAL SPEED V OF 150-300 M./MIN.